An example of a conventional air-cooled absorption-type air conditioning apparatus is disclosed in Japanese patent Hei 6-21743. The apparatus disclosed in that patent includes a first cold/warm water heat exchanger, an outer pipe, a first spray mechanism, and a second spray mechanism. The first cold/warm water heat exchanger is formed using a portion of the circulation passage for the cold/warm water which becomes the temperature control medium in a room air-conditioning unit. The outer pipe surrounds the outer circumference of the circulation passage at a certain distance from the outer circumference of the circulation passage. The first spray mechanism sprays a liquid coolant or high-concentration liquid over the outer surface of the first cold/warm water heat exchanger. The second spray mechanism sprays a liquid coolant or high-concentration liquid over the inner surface of the outer pipe. During a cooling operation, the following steps take place. Coolant vapor flows from a low temperature regenerator to a condenser, at which the coolant vapor is condensed into a liquid coolant. Then the liquid coolant is sprayed over the outer surface of the first cold/warm water heat exchanger by the first spray mechanism, and a high-concentration liquid, which is separated at the low temperature regenerator, is sprayed onto the inner surface of the outer pipe by the second spray mechanism. Evaporation of the liquid coolant cools the water within the first cold/warm water heat exchanger. The high-concentration liquid, which is sprayed onto the inner surface of the outer pipe, absorbs the coolant vapor, thereby generating heat. The heat generated by the absorption of the coolant vapor is removed by air flowing over the outer surface of the outer pipe.
During a heating operation, the following steps take place. Coolant vapor, which is separated by a phase separator after being heated in a high temperature regenerator, exchanges heat with cold/warm water, which flows through a second cold/warm water heat exchanger in a heater. The second cold/warm water heat exchanger is formed using a portion of the cold/warm water circulation passage. Liquified coolant is sprayed onto the inner surface of the outer pipe by the second spray mechanism. The high-concentration liquid which is separated by a phase separator after being heated by the high temperature regenerator, is sprayed over the outer surface of the first cold/warm water heat exchanger by the first spray mechanism. The liquid coolant absorbs heat from the air on the outer surface on the outer pipe and evaporates as it is sprayed on to the outer surface of the first cold/warm water heat exchanger. The vapor produced by the evaporation of the liquid coolant is then absorbed by the high-concentration liquid, generating heat which warms the cold/warm water.
In the conventional air-conditioning apparatus described above, fins are placed in a horizontal orientation on the outer pipe of the evaporation-absorption unit. Water from condensation or rain tends to get trapped between the horizontal fins. For example, during a heating operation, condensation occurs on the fins because the outer pipe is chilled when the liquid coolant on the inner surface of the outer pipe evaporates. The condensation is likely to remain between the fins and in some conditions may freeze to form frost. The condensation or frost prevents air, blown by a fan, from efficiently transmitting heat to the fins. In addition, water from rain or condensation tends to corrode the fins and the outer pipe, adversely affecting the reliability and the durability of the apparatus.